public class MySingleList implements IList{
    //节点的内部类
    static class ListNode{
        public int val;
        public ListNode next;
        public ListNode(int val){
            this.val=val;
        }
    }

    public ListNode head;
    public void createList(){
        ListNode node1=new ListNode(12);
        ListNode node2=new ListNode(23);
        ListNode node3=new ListNode(34);
        ListNode node4=new ListNode(45);
        ListNode node5=new ListNode(56);

        node1.next=node2;
        node2.next=node3;
        node3.next=node4;
        node4.next=node5;
        this.head=node1;
    }
    @Override
    public void addFirst(int data) {
        ListNode node=new ListNode(data);
        if(this.head==null){
            this.head=node;
        }else{
            node.next=this.head;
            this.head=node;
        }
    }

    @Override
    public void addLast(int data) {
        ListNode node=new ListNode(data);
        ListNode cur=this.head;
        if(this.head==null){
            this.head=node;
        }else{
            while(cur.next!=null){
                cur=cur.next;
            }
            cur.next=node;
        }

    }

    @Override
    public void addIndex(int index, int data) {
        if(index<0||index>size()){
            return;
        }
        if(index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        ListNode cur=SearchPrev(index);
        ListNode node=new ListNode(data);
        node.next=cur.next;
        cur.next=node;
    }
    private ListNode SearchPrev(int index){
        ListNode cur=this.head;
        int count=0;
        while(count!=index-1){
            cur=cur.next;
            count++;
        }
        return cur;
    }

    @Override
    public boolean contains(int key) {
        return false;
    }

    @Override
    public void remove(int key) {
        ListNode cur=findPrev(key);
        if(cur==null){
            System.out.println("没有要删除的数字");
        }
        ListNode del=cur.next;
        cur.next=del.next;
    }
    private ListNode findPrev(int key){
        ListNode cur=this.head;
        while(cur.next!=null){
            if(cur.next.val==key){
                return cur;
            }
        }
        return null;
    }
    @Override
    public void removeAllKey(int key) {
        if(this.head==null){
            return;
        }
        ListNode prev=head;
        ListNode cur=head.next;
        while(cur!=null){
            if(cur.val==key){
                prev.next=cur.next;
                cur=cur.next;
            }else{
                prev=cur;
                cur=cur.next;
            }
        }
        if(head.val==key){//头节点==key
            head=head.next;
        }
    }

    @Override
        public ListNode reverseList() {//链表反转
            if(head==null){
                return null;
            }
            if(head.next==null){//一个节点
                return head;
            }
            ListNode cur=head.next;
            head.next=null;
            while(cur!=null){
                ListNode curNext=cur.next;//记录之后节点
                cur.next=head;//头插
                head=cur;
                cur=curNext;
            }
            return head;
    }

    @Override
    public int size() {
        int count=0;
        ListNode cur=this.head;
        while(cur!=null){
            count++;
            cur=cur.next;
        }
        System.out.println();
        return count;
    }

    @Override
    public void clear() {//清除链表
        ListNode cur=head;
        while(cur!=null){
            ListNode curNext=cur.next;
            cur.next=null;
            cur=curNext;
        }
        head=null;
    }

    @Override
    public void display() {
        ListNode cur=this.head;
        while(cur!=null){
            System.out.println(cur.val+"");
            cur=cur.next;
        }
        System.out.println();
    }

    public ListNode middleNode(){//找链表中间节点
        ListNode cur=head;
       int len=size();
        for (int i = 0; i < len/2; i++) {
            cur=cur.next;
        }
        return cur;
    }

    public ListNode middleNode1(){
        ListNode fast=head;
        ListNode slow=head;
        while(fast!=null&&fast.next!=null){//分别是偶数和奇数的情况
            fast=fast.next.next;
            slow=slow.next;
        }
        return slow;
    }

    public ListNode FindKthTail(int k){//找倒数第K个节点
        if(k<=0||head==null){
            return null;
        }
        ListNode fast=head;
        ListNode slow=head;
        int count=0;
        while(k-1!=count){
            fast=fast.next;
            if(fast==null){
                return null;
            }
            count++;
        }
        while(fast.next!=null) {
            fast = fast.next;
            slow = slow.next;
        }
        return slow;
    }
    public void display(ListNode newHerad) {//指定位置打印
        ListNode cur=this.head;
        while(cur!=null){
            System.out.println(cur.val+"");
            cur=cur.next;
        }
        System.out.println();
    }
}

